Customizing Plum Analytics Artifact Widget Block

Hello there, I am new at the use of OJS, so I’m looking for guidance

We are using OJS version 3.1.1.2, and implementing the Plum Analytics Artifact Widget Block, its working fine, but as you can see, the background of the Plum Analytics (pkp_block) is different than the other custom blocks.
Screenshot_20200701_163154|315x500

How can I make the background in the Plum Analytics Artifact Widget Block look the same than the other blocks?

Thank you in advance